Reference : Extracting tables from multiple PDFs
Some close vote raised the question of techniques and particularly data extraction techniques as on- or off-topic. One can argue some other sites, such as SO, already have such questions.
I would say they are on-topic, because they are useful to Open Data users, but also, more simply, because it is part of the "Open" in Open Data. Indeed, better extraction techniques make for more open data.
Should data extraction techniques be on- or off-topic?